ARM: dts: msm: add PM8916 QPNP controlled regulators for MSM8939

Change stub-regulator devices to qpnp-regulator devices for MSM8939 so
that hardware can output the actual voltage to consumers.

Bump up S1, S2 to lock Cx power rail at max voltage. Bump up S4
regulator to max voltage to prevent S4 going to low voltage to respect
headroom requirement of sub-regulated regulators.

Change-Id: I155e6d76fc9d931318d215249837296dbee5e117
Signed-off-by: Fenglin Wu <fenglinw@codeaurora.org>